Energy storage device with wraparound encapsulation

ABSTRACT

Approaches herein provide encapsulation of a micro battery cell of a cell matrix. The micro battery cell includes an active device, such as a thin film device, formed atop a first side of a substrate. An encapsulant may be formed over the active device, wherein the encapsulant adheres to the active device and to a second side of the substrate. In some approaches, the encapsulant penetrates a plurality of openings provided through the substrate, thus allowing the encapsulant to form along the second side of the substrate to fully envelope the micro battery cell.

RELATED APPLICATIONS

This application claims priority to U.S. provisional patent application62/322,415, filed Apr. 14, 2016, entitled Volume Change AccommodatingTFE Materials, and incorporated by reference herein in its entirety.

FIELD

The present embodiments relate to thin film encapsulation (TFE)technology used to protect active devices and, more particularly, to anenergy storage device with a wraparound encapsulant.

BACKGROUND

Thin film encapsulation (TFE) technology is often employed in deviceswhere the devices are primarily electrical devices or electro-opticaldevices, such as Organic Light Emitting Diodes (OLED). Other thanpossibly experiencing a generally small global thermal expansion fromheat generation during device operation, the electrical devices andelectro-optical devices do not exhibit volume changes during operationsince just electrons and photons are transported within the devicesduring operation. Such global effects due to global thermal expansion ofa device may affect in a similar fashion every component of a givendevice including the TFE, and thus, may not lead to significant internalstress. In this manner, the functionality of the TFE in a purelyelectrical device or electro-optic device is not generally susceptibleto stresses from non-uniform expansion during operation.

Notably, in an electrochemical device (“chemical” portion), matter suchas elements, ions, or other chemical species having a physical volume(the physical volume of electrons may be considered to be approximatelyzero) are transported within the device during operation with physicalvolume move. For known electrochemical devices, e.g., thin filmbatteries (TFB) based upon lithium (Li), Li is transported from one sideto the other side of a battery as electrons are transported in anexternal circuit connected to the TFB, where the electrons move in anopposite direction to the chemical and elements. One particular exampleof the volume change experienced by a Li TFB occurs when charging a thinfilm battery having a lithium cobalt oxide (LiCoO₂) cathode (˜15 μm to17 μm thick LiCoO₂). An amount of Li equivalent to several micrometersthick layer, such as 6 micrometers, may be transported to the anode whenloading is approximately 1 mAhr/cm². When Li returns to the cathode sidein a discharge process, a comparable volume reduction may result on theanode side (assuming 100% efficiency). The cathode side may also undergoa volume change in an opposite manner, although such changes aregenerally smaller as compared to the anode side.

As such, known TFE approaches are lacking the ability to accommodatesuch volume change in a robust manner, to ensure the TFE continues toprovide protection of the electrochemical device during repeated cyclingof the device.

With respect to these and other considerations the present disclosure isprovided.

SUMMARY OF THE DISCLOSURE

In view of the foregoing, approaches herein provide encapsulation of amicro battery cell of a cell matrix. The micro battery cell includes anactive device (e.g., a thin film energy storage device) formed atop afirst side of a substrate, and an encapsulant formed over the activedevice, wherein the encapsulant adheres to the active device and to asecond side of the substrate. In some approaches, the encapsulantpenetrates a plurality of openings provided through the substrate, thusallowing the encapsulant to form along the second side of the substrateto fully envelope and seal the micro battery cell.

An exemplary energy storage device in accordance with the presentdisclosure may include a thin film device formed on a first side of asubstrate, and an encapsulant formed over the thin film device, whereinthe encapsulant covers the thin film device and a second side of thesubstrate.

An exemplary micro battery cell in accordance with the presentdisclosure may include an active device coupled to a first side of asubstrate, and an encapsulant formed over the active device, wherein theencapsulant adheres to the active device and to a second side of thesubstrate.

An exemplary method for forming an energy storage device in accordancewith the present disclosure may include providing a thin film device ona first side of a substrate, forming a plurality of openings through thesubstrate, and forming a thin film encapsulant over the thin filmdevice, wherein the thin film encapsulant is formed along a surfacedefining one or more of the plurality of openings, and wherein the thinfilm encapsulant adheres to the thin film device and covers a secondside of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate exemplary approaches of thedisclosed embodiments so far devised for the practical application ofthe principles thereof, wherein:

FIG. 1A depicts a top view of a micro battery cell of a cell matrix inaccordance with exemplary embodiments of the present disclosure;

FIG. 1B depicts a side cross-sectional view of the micro battery celland cell matrix of FIG. 1A in accordance with exemplary embodiments ofthe present disclosure;

FIG. 2A depicts a top view of an active device formed atop a substrateof a micro battery cell in accordance with exemplary embodiments of thepresent disclosure;

FIG. 2B depicts a side cross-sectional view of the active device formedatop the substrate of the micro battery cell of FIG. 2A in accordancewith exemplary embodiments of the present disclosure;

FIG. 3A depicts a top view of an encapsulant formed over a cell matrixin accordance with exemplary embodiments of the present disclosure;

FIG. 3B depicts a side cross-sectional view of the encapsulant formedover the cell matrix FIG. 3A in accordance with exemplary embodiments ofthe present disclosure;

FIG. 4A depicts a top view of a first layer of an encapsulant formedover an active device of a micro battery cell in accordance withexemplary embodiments of the present disclosure;

FIG. 4B depicts a side cross-sectional view of the first layer of theencapsulant formed over the active device of the micro battery cell FIG.4A in accordance with exemplary embodiments of the present disclosure;

FIG. 5A depicts a top view of a second layer of an encapsulant formedover a micro battery cell in accordance with exemplary embodiments ofthe present disclosure;

FIG. 5B depicts a side cross-sectional view of the second layer of theencapsulant formed over the micro battery cell of FIG. 5A in accordancewith exemplary embodiments of the present disclosure;

FIG. 6A depicts a top view of an active device atop a substrate of amicro battery cell in accordance with exemplary embodiments of thepresent disclosure;

FIG. 6B depicts a side cross-sectional view of the active device atopthe substrate of the micro battery cell of FIG. 6A in accordance withexemplary embodiments of the present disclosure;

FIG. 7A depicts a top view of a plurality of openings formed adjacent anactive device of a micro battery cell in accordance with exemplaryembodiments of the present disclosure;

FIG. 7B depicts a side cross-sectional view of the plurality of openingsformed adjacent the active device of the micro battery cell of FIG. 7Ain accordance with exemplary embodiments of the present disclosure;

FIG. 8A depicts a top view of a double sided active device formed on asubstrate of a micro battery cell in accordance with exemplaryembodiments of the present disclosure;

FIG. 8B depicts a side cross-sectional view of the double sided activedevice formed on a substrate of the micro battery cell of FIG. 8A inaccordance with exemplary embodiments of the present disclosure;

FIG. 9A depicts a top view of an encapsulant formed over the doublesided active device of in accordance with exemplary embodiments of thepresent disclosure; and

FIG. 9B depicts a side cross-sectional view of the encapsulant formedover the double sided active device of FIG. 9A in accordance withexemplary embodiments of the present disclosure.

The drawings are not necessarily to scale. The drawings are merelyrepresentations, not intended to portray specific parameters of thedisclosure. The drawings are intended to depict exemplary embodiments ofthe disclosure, and therefore are not be considered as limiting inscope. In the drawings, like numbering represents like elements.

Furthermore, certain elements in some of the figures may be omitted, orillustrated not-to-scale, for illustrative clarity. The cross-sectionalviews may be in the form of “slices”, or “near-sighted” cross-sectionalviews, omitting certain background lines otherwise visible in a “true”cross-sectional view, for illustrative clarity. Furthermore, forclarity, some reference numbers may be omitted in certain drawings.

DETAILED DESCRIPTION

One or more approaches in accordance with the present disclosure willnow be described more fully hereinafter with reference to theaccompanying drawings, where embodiments of devices and methods areshown. The approaches may be embodied in many different forms and arenot to be construed as being limited to the embodiments set forthherein. Instead, these embodiments are provided so this disclosure willbe thorough and complete, and will fully convey the scope of the devicesand methods to those skilled in the art.

For the sake of convenience and clarity, terms such as “top,” “bottom,”“upper,” “lower,” “vertical,” “horizontal,” “lateral,” and“longitudinal” will be used herein to describe the relative placementand orientation of these components and their constituent parts, eachwith respect to the geometry and orientation of the energy storagedevice as appearing in the figures. The terminology will include thewords specifically mentioned, derivatives thereof, and words of similarimport.

As used herein, an element or operation recited in the singular andproceeded with the word “a” or “an” is to be understood as includingplural elements or operations, until such exclusion is explicitlyrecited. Furthermore, references to “one embodiment” of the presentdisclosure are not intended as limiting. Additional embodiments may alsoincorporating the recited features.

As further described herein, the present disclosure relates to thin filmencapsulation (TFE) technology used to minimize ambient exposure ofactive devices, for example, during the fabrication and manufacturing ofthin film solid state batteries (TFB) using a maskless patterningprocess. By improving robustness of the encapsulant(s) battery cell,volume expansion caused by moisture contamination may be mitigated.Specifically, provided herein is a micro battery cell including anactive device formed on one or more sides of a substrate. An encapsulantmay be formed over the active device, wherein the encapsulant adheres tothe active device and to a second side of the substrate. In cases wherea second active device is provided on the second side of the substrate,the encapsulant further adheres to and covers the second active device.In some approaches, the encapsulant penetrates a plurality of openingsprovided through the substrate, thus allowing the encapsulant to extendalong the second side of the substrate and fully encapsulate the microbattery cell. As a result, the cohesion force of the wrap aroundencapsulant may accommodate cell volume expansion and swelling, and maymaintain good surface adhesion to other cell stack materials. In someapproaches, a vapor or a liquid phase coating technique may be used toform the wraparound encapsulant.

Turning now to FIGS. 1A-B, respective top and side cross-sectional viewsof a micro battery cell 100 of a cell matrix 110 according to variousembodiments of the disclosure will be described in greater detail. Asshown, the cell matrix 110 may include a plurality of micro batterycells of a substrate 112, such as micro battery cells 114 and 116, inaddition to the micro battery cell 100. As one will appreciate, the cellmatrix 110 may include thousands of micro battery cells, and theembodiments herein are not limited to the number of cells depicted inthe figures. Furthermore, the techniques described herein with respectto the micro battery cell 100 may be scaled for larger energy storagedevices as well. Hereinafter, just the micro battery cell 100 will bedescribed for purposes of brevity.

As shown, a plurality of openings 120 may be formed through thesubstrate 112, for example, along an outer perimeter of the microbattery cell 100 as delineated by broken lines 122, 123, 124, and 125.As will be described in greater detail below, the plurality of openings120 allow a subsequently formed encapsulant to penetrate through thesubstrate 112 and wrap along a second side 126 (e.g., a bottom surface)of the substrate 112. In some embodiments, each of the openings 120 hasa generally rectangular shape, and extends just partially along theperimeter of the micro battery cell 100 so as to leave remaining aplurality of corner sections 128 for structural support of the substrate112. The plurality of corner sections 128 hold the micro battery cell100 in place in the matrix 110, and may later be severed, thus allowinga thin-film storage device of the micro battery cell 100 to be excised.

In some embodiments, the substrate 112 serves as a support for an energystorage device, such as a thin film battery, and is made from a materialsuitably impermeable to environmental elements. The substrate 112 has arelatively smooth processing surface for forming thin films thereupon,and also has adequate mechanical strength to support the deposited thinfilms at fabrication temperatures and at battery operationaltemperatures. For example, the substrate 112 may be an insulator,semiconductor, or a conductor, depending upon the intended electricalproperties of the exterior surfaces. More specifically, the substrate112 may be made from a ceramic, metal, or glass, for example, aluminumoxide, silicate glass, or even aluminum or steel, depending on theapplication.

In one embodiment, the substrate 112 may include mica, a layeredsilicate having a muscovite structure and a stoichiometry ofKAl₃Si₃O₁₀(OH)₂. Mica has a six-sided planar monoclinic crystallinestructure with good cleavage properties along the direction of the largeplanar surfaces. Because of the crystal structure of mica, the substrate112 may be split into thin foils along its basal lateral cleavage planesto provide thin substrates having surfaces smoother than most chemicallyor mechanically polished surfaces.

Turning now to FIGS. 2A-B, respective top and side cross-sectional viewsof the micro battery cell 100 of the cell matrix 110 according tovarious embodiments of the disclosure will be described in greaterdetail. As shown, an active device, such as a thin film device 130, isformed on the substrate 112 along a first side 132 (e.g., a top surface)thereof. The thin film device 130 may constitute an electrochemicaldevice such as a thin film battery, micro battery device, electrochromicwindow, or other electrochemical device. As shown, the thin film device130 has a generally rectangular shape, wherein the plurality of openings120 are formed adjacent each side thereof. Each of the plurality ofcorner sections 128 of the substrate 112 may extend outwardly from thethin film device 130.

In some embodiments, the thin film device 130 may include the substrate112 and a source region disposed on the substrate 102. The source regionmay represent a cathode of the thin film device 130, wherein the sourceregion may act as a source of a diffusant such as lithium, and whereinthe diffusant may reversibly diffuse to and from the source region. Thethin film device 130 may also include an intermediate region (notspecifically shown) disposed on the source region, and a selectiveexpansion region disposed on the intermediate region. The selectiveexpansion region may be an anode region of the thin film device 130. Insome embodiments, the thin films of each layer of the thin film device130 may be formed by thin film fabrication processes, such as physicalor chemical vapor deposition methods (PVD or CVD), oxidation,nitridation or electro-plating.

Although not shown, in some embodiments, an electrolyte layer may beprovided between the anode and the cathode of the thin film device 130.In some embodiments, the electrolyte layer may be, for example, anamorphous lithium phosphorus oxynitride film, referred to as a LiPONfilm. In one non-limiting embodiment, the LiPON film is of the formLi_(x)PO_(y)N_(z). In one approach, the electrolyte layer has athickness of from approximately 0.1 microns to 5 microns. Theelectrolyte thickness is suitably large to provide adequate protectionfrom shorting of the cathode and the anode, and suitably small to reduceionic pathways to minimize electrical resistance and reduce stress.

In some embodiments, the anode and the cathode of the thin film deviceeach include an electrochemically active material, such as amorphousvanadium pentoxide V₂O₅, or one of several crystalline compounds, suchas TiS₂, LiMnO₂, LiMn₂O₂, LiMn₂O₄, LiCoO₂ and LiNiO₂. In onenon-limiting embodiment, the anode is made from Li and the cathode ismade from LiCoO₂. A suitable thickness for the anode or cathode may befrom approximately 0.1 microns to 50 microns.

The thin film device 130 may also include one or more adhesion layers(not shown) deposited on the substrate 112 or the surfaces of any of theother layers of the thin film device 130, to improve adhesion ofoverlying layers. The adhesion layer may comprise a metal such as, forexample, titanium, cobalt, aluminum, or other metals. In someembodiments, the adhesion layer may be a ceramic material such as, forexample, LiCoO_(x), having a stoichiometry of LiCoO₂.

Turning now to FIGS. 3A-B, respective top and side cross-sectional viewsof the micro battery cell 100 of the cell matrix 110 with an encapsulant140 formed thereon according to various embodiments of the disclosurewill be described in greater detail. As shown, the encapsulant 140 isformed over the micro battery cell 100 so the encapsulant 140 adheres tothe thin film device 130, and to the first side 132 of the substrate112, as well as along a set of sidewalls 142 defining the openings 120.The encapsulant 140 is intended to permeate and extend through theopenings 120 and continue along the second side 126 of the substrate 112until the cell matrix 110 is fully encased by the encapsulant 140. Invarious embodiments, the encapsulant 140 may expand to partially orcompletely fill the openings 120.

The encapsulant 140 may be a soft and pliable, physical volumeaccommodating layer capable of conforming to the geometries of the microbattery cell 100, as well as accommodating volume changes of the layersof the thin film device 130. In one embodiment, the encapsulant 140 ismade from a polymer material having good sealing properties to protectthe sensitive battery components of the thin film device 130 from theexternal environment. For example, the polymer material of theencapsulant 140 may be selected to provide a good moisture barrier, andhave an adequately low water permeability rate to allow the layers ofthe thin film device 130 to survive in humid external environments.

In exemplary embodiments, the encapsulant 140 may include a parylenevapor condensation coating applied simultaneously to the first andsecond sides 132, 126 of the substrate 112. Alternatively, theencapsulant may include dip coated polymers or dielectric materialsapplied simultaneously to the first and second sides 132, 126 of thesubstrate 112, sprayed on or powder coated polymers or dielectriccoatings, or CVD dielectric coatings. The encapsulant 140 may be formedusing a vapor or a liquid phase coating technique to provide theintended wraparound encapsulation. This has the advantage of using theinherent cohesive strength of the encapsulant 140 to hold theencapsulant 140 in place when the thin film device 130 swells, forexample, when charged.

In various embodiments, the encapsulant 140 may have varied dimensionsin order to accommodate changes in volume or thickness of differentmaterials in expansion regions. For example, in the case the anode or aportion of the anode of the thin film device 130 constitutes a selectiveexpansion region, the encapsulant 140 may expand or contract inthickness to accommodate the increase or decrease in anode thickness,resulting in less stress, less mechanical failure, and better protectionof the layers of the thin film device 130.

In other embodiments, the encapsulant 140 may be a thermoset orthermoplastic polymer undergoing a chemical change during processing tobecome “set” to form a hard solid material. The thermoset polymer can bea highly cross-linked polymer having a three-dimensional network ofpolymer chains. Thermoset polymer materials undergo a chemical as wellas a phase change when heated. Due to their tightly cross-linkedstructure, thermoset polymers may be less flexible than mostthermoplastic polymers.

In still other embodiments, the encapsulant 140 may be a thermoplasticpolymer, such as a melt processable material remaining malleable at hightemperatures. The thermoplastic polymer is selected to soften attemperatures of from approximately 65° C. to 200° C. to allow moldingthe polymer material around the battery cell without thermally degradingthe battery cell. A suitable thermoplastic polymer includes, forexample, polyvinylidene chloride (PVDC).

Turning now to FIGS. 4A-5B, respective top and side cross-sectionalviews of an encapsulant 240 formed over a cell matrix 210 according tovarious embodiments of the disclosure will be described in greaterdetail. In this embodiment, the encapsulant 240 may be a thin filmencapsulant including a plurality of encapsulation layers. For example,as shown in FIGS. 4A-B, a first layer 241 of the encapsulant 240 may beprovided over a thin film device 230, and terminates along a first side232 of a substrate 212. The first layer 241 adheres to the exposedsurfaces of the thin film device 230, yet does not extend into openings220 in the embodiment shown. The first layer 241 of the encapsulant 240may be a polymer having good sealing properties to protect the sensitivebattery components of the thin film device 230 from the externalenvironment. In some embodiments, the first layer 241 of the encapsulant240 may be sprayed on or powder coated polymers or dielectric coatings,or CVD dielectric coatings.

As shown in FIGS. 5A-B, a second layer 243 of the encapsulant 240 maythen be formed over the first layer 241. The second layer 243 may beformed over all of the micro battery cell 200 so the second layer 243adheres to a top side of the first layer 241, the first side 232 of thesubstrate 212, and along sidewalls 242 of the openings 220. The secondlayer 243 of the encapsulant 240 is intended to extend through theopenings 220 and continue along the second side 226 of the substrate 212until the cell matrix 210 is fully encased by the encapsulant 240. Invarious embodiments, the second layer 243 of the encapsulant 240 mayexpand to partially or completely fill the openings 220.

The second layer 243 of the encapsulant 240 may include a parylenepolymer layer, dip coated polymers or dielectric layers/materials,sprayed on or powder coated polymers or dielectric coatings, or CVDdielectric coatings. The second layer 243 of the encapsulant 240 may beformed using a vapor or a liquid phase coating technique to provide theintended wraparound encapsulation. This has the advantage of using theinherent cohesive strength of the second layer 243 of the encapsulant240 to hold the encapsulant 240 in place in the case the thin filmdevice 230 expands. In various embodiments, the first layer 241 and thesecond layer 243 of the encapsulant 240 may be the same or differentmaterials.

Turning now to FIGS. 6A-7B, respective top and side cross-sectionalviews of a micro battery cell 300 of a cell matrix 310 according toanother embodiment of the disclosure will be described in greaterdetail. As shown in FIGS. 6A-B, an active device, such as a thin filmdevice 330, is formed on a substrate 312, for example, along a firstside 332 thereof. The thin film device 330 may constitute anelectrochemical device such as a thin film battery, micro batterydevice, electrochromic window, or other electrochemical device.

In this embodiment, the thin film device 330 may be formed atop thesubstrate 312 prior to subsequent formation of a plurality of openings320 through the substrate 312, as shown in FIGS. 7A-B. An encapsulantmay then be formed over the micro battery cell 300, resulting in thestructure demonstrated in FIGS. 3A-B or FIGS. 4A-B depending on whetherthe encapsulant is one layer or multiple layers.

Turning to FIGS. 8A-B, respective top and side cross-sectional views ofa micro battery cell 400 of a cell matrix 410 according to variousembodiments of the disclosure will now be described. As shown, an activedevice, such as a thin film device 430, is formed on the substrate 412along a first side 432 (e.g., a top surface) thereof. As further shown,a second thin film device 431 may be formed on a second side 426 of thesubstrate 412. As such, micro battery cell 400 may be a double sidedcell, wherein the thin film device 430 and the second thin film device431 constitute an electrochemical device such as a thin film battery,micro battery device, electrochromic window, or other electrochemicaldevice. As shown, the thin film device 430 and the second thin filmdevice 431 have a generally rectangular shape, wherein a plurality ofopenings 420 are formed adjacent each side thereof. Each of a pluralityof corner sections 428 of the substrate 412 may extend outwardly fromthe thin film device 430 and the second thin film device 431.

Turning to FIGS. 9A-B, respective top and side cross-sectional views ofthe micro battery cell 400 of the cell matrix 410 with an encapsulant440 formed thereon according to various embodiments of the disclosurewill now be described. As shown, the encapsulant 440 is formed over themicro battery cell 400 so the encapsulant 440 adheres to and covers thethin film device 430 and the second thin film device 432, as well as anyexposed portions of the first and second sides 432, 426 of the substrate412. The encapsulant 440 is further formed along a set of sidewalls 442defining the openings 420 through the substrate 412. In exemplaryembodiments, the encapsulant 440 is intended to permeate or extendthrough the openings 420 and continue along the second side 426 of thesubstrate 412 and the second thin film device 432 until the cell matrix410 is fully encased by the encapsulant 440. The encapsulant 440 mayexpand to partially or completely fill the openings 420. In variousembodiments, the encapsulant 440 is a thin film encapsulant comprisingone or more layers.

In view of the foregoing, at least the following advantages are achievedby the embodiments disclosed herein. A first advantage is theimprovement in encapsulation anchoring to the substrate and thereduction of encapsulant delamination responsible for the prematureintroduction of unwanted moisture and gas penetration to a thin filmdevice contained therein. A second advantage includes the use of theencapsulant's self-cohesive strength to hold the encapsulation filmlayer(s) in place in the event the micro battery cell stack swells, forexample, when charged.

While certain embodiments of the disclosure have been described herein,the disclosure is not limited thereto, as the disclosure is as broad inscope as the art will allow and the specification may be read likewise.Therefore, the above description is not to be construed as limiting.Instead, the above description is merely as exemplifications ofparticular embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

1. An energy storage device comprising: a thin film device formed on afirst side of a substrate; and an encapsulant formed over the thin filmdevice, wherein the encapsulant covers the thin film device and a secondside of the substrate.
 2. The energy storage device of claim 1, whereinthe encapsulant is formed along the first side of the substrate.
 3. Theenergy storage device of claim 1, wherein the encapsulant comprises aplurality of encapsulation layers.
 4. The energy storage device of claim3, wherein a first layer of the plurality of encapsulation layers isformed over the thin film device and terminates along the first side ofthe substrate, and wherein a second layer of the plurality ofencapsulation layers is formed over the first layer of the plurality ofencapsulation layers and extends along the second side of the substrate.5. The energy storage device of claim 4, wherein the second layer is oneof: a parylene polymer layer, and a dielectric layer.
 6. The energystorage device of claim 1, further comprising a second thin film deviceformed on the second side of the substrate, wherein the encapsulantcovers the second thin film device.
 7. A micro battery cell, the microbattery cell comprising: an active device coupled to a first side of asubstrate; and an encapsulant formed over the active device, wherein theencapsulant adheres to the active device and to a second side of thesubstrate.
 8. The micro battery cell of claim 7, further comprising asecond active device coupled to the second side of the substrate,wherein the encapsulant adheres to the second active device.
 9. Themicro battery cell of claim 7, wherein the encapsulant is a thin filmencapsulant comprising a plurality of encapsulation layers, wherein afirst layer of the plurality of encapsulation layers is formed over theactive device and terminates along the first side of the substrate, andwherein a second layer of the plurality of encapsulation layers isformed over the first layer of the plurality of encapsulation layers andextends along the second side of the substrate.
 10. The micro batterycell of claim 9, wherein the second layer is one of: a parylene polymerlayer, and a dielectric layer.
 11. The micro battery cell of claim 7,further comprising a plurality of openings formed through the substrate,wherein the encapsulant is formed through the plurality of openings. 12.The micro battery cell of claim 11, wherein the substrate comprises aplurality of corner sections extending outwardly from the active device,wherein the plurality of openings extend between the plurality of cornersections.
 13. The micro battery cell of claim 11, wherein the pluralityof openings are formed along an outer perimeter of the micro batterycell.
 14. A method of forming an energy storage device, comprising:providing a thin film device on a first side of a substrate; forming aplurality of openings through the substrate; and forming a thin filmencapsulant over the thin film device, wherein the thin film encapsulantis formed along a surface defining one or more of the plurality ofopenings, and wherein the thin film encapsulant adheres to the thin filmdevice and covers a second side of the substrate.
 15. The method ofclaim 14, further comprising: forming a first layer of the thin filmencapsulant over the thin film device, wherein the first layer of thethin film encapsulant terminates along the first side of the substrate;and forming a second layer of the thin film encapsulant over the firstlayer of the thin film encapsulant, wherein the second layer of the thinfilm encapsulant extends along the second side of the substrate.
 16. Themethod of claim 14, further comprising providing a second thin filmdevice on the second side of the substrate, wherein the thin filmencapsulant is formed over and adheres to the second thin film device.17. The method of claim 14, further comprising forming the thin filmencapsulant using one of: vapor deposition, and liquid coating.
 18. Themethod of claim 14, further comprising forming the plurality of openingsthrough the substrate after the thin film device is formed atop thesubstrate.
 19. The method of claim 14, further comprising forming theplurality of openings adjacent a side of the thin film device.
 20. Themethod of claim 14, further comprising providing a plurality of cornersections of the substrate extending outwardly from the thin film device,wherein the plurality of openings extend between the plurality of cornersections.